1. Field of the Invention
The present invention relates to a throttle control device equipped with a throttle valve for controlling a flow rate of a fluid, in particular, to a throttle control device for controlling the flow rate of air, for example, intake air to be supplied to an automotive engine.
2. Description of the Related Art
Japanese Laid-Open Patent Publication No. 2001-132495 discloses a conventional throttle control device. In the throttle control device disclosed in this gazette, a throttle valve is arranged in an intake passage formed in a throttle body and is rotated by a motor. As the throttle valve rotates, the intake passage is incrementally opened and closed to thereby control the intake air amount. Further, this device has a gear mechanism including a counter gear arranged in a gear accommodating chamber provided in the throttle body. The counter gear transmits the driving force of the motor to the throttle valve. A counter shaft rotatably supporting the counter gear is fixed to the wall of the gear accommodating chamber by press-fitting or similar method (See the description on page 3 and FIG. 1).
The conventional throttle control device requires a counter shaft, a separate component not part of the throttle body. Further, it also requires a press-fitting operation in order to attach the counter shaft. As a result of the assembly process, the conventional throttle control device involves a relatively high cost. Although it might be possible to form the throttle body of resin and assemble the countershaft by an insert molding process, this would also involve a relatively high assembly cost similar to the above process.